$275 at twice the time of simply driving, and factor in time to deal with airports, doesn't sound reasonable at all to me. Depending where in Allentown you'll be going, you'll probably need a vehicle, which will add to both the time and expense.

One time when I was flying back to AVP, there were some guys on the PHL-AVP flight who did something like that. The FA's had a good laugh about it, and even told the gate agents at AVP, who continued to give them a hard time.